An optoelectronic component is designed for converting electrical energy into electromagnetic radiation, such as into the visible light, for example, or for the reverse process. Reference may be made in each case to an emitter device or a detector device. One example of an electromagnetic component in the form of an emitter device is a light-emitting component, more particularly a light-emitting diode (LED). The light-emitting component typically comprises electrodes with an active zone disposed between them. Via the electrodes, the light-emitting component can be supplied with an electric current which in the active zone is converted into optical energy, i.e., electromagnetic radiation. The optical energy is outcoupled from the light-emitting component via a radiation outcoupling area.
One particular light-emitting component is the organic, light-emitting component (Organic Light Emitting Device or OLED). An OLED has an organic layer in the active layer in order to convert electrical energy into electromagnetic radiation. When the OLED is contacted with a current source via the electrodes, different types of charge carrier are injected into the organic layer. Positive charge carriers, also referred to as holes, migrate from the anode toward the cathode through the organic layer, while electrons migrate through the organic layer from the cathode toward the anode. In the course of this process, excitation states develop in the organic layer, in the form of electron-hole pairs, known as excitons, which decompose with emission of electromagnetic radiation. An organic light-emitting component of this kind is known from German Patent Publication No. 101 35 513 A1, for example.
The electromagnetic radiation emitted from the organic layer is outcoupled from the OLED via at least one of the electrodes, in other words via the anode or via the cathode. Correspondingly, the electrode must be transparent in respect of the emitted radiation—that is, it must have a high transmission coefficient for the electromagnetic radiation. For electromagnetic radiation in the visible light range, for example, thin metal films (TMFs) based on silver (Ag), gold (Au), or magnesium (Mg) are used for a transparent electrode material. Also possible is the use of transparent conductive oxides (TCOs) as electrode material, such as indium tin oxide (ITO) or aluminum-doped zinc oxide (AZO), for example. Further conceivable are composite electrodes which have a layer stack composed of TMFs and/or TCOs, for example.
In order to inject the charge carriers from the electrode into the active layer, it is common to provide interlayers which bring about charge carrier transport from the electrode into the active layer. A charge transport layer of this kind is desirable in particular on the anode side, in order to boost the injection of holes into the active layer. The charge transport layer provided on the anode side is also referred to as a hole transport layer (HTL). A thick HTL has the advantage, in the operation of the OLED, of suppressing spontaneous short circuits, where electrons—without being combined with holes in the active layer to form excitons—cross the organic layer and reach the anode directly. To be able to ensure the performance of OLED components having a thick HTL, in respect of efficiency or else lifetime, for example, it is advantageous if the relatively thick charge transport layer between anode and active layer is preferably transparent.